Ono pincer ligands and ono pincer ligand comprising metal complexes

ABSTRACT

Embodiments of the invention are directed to ONO pincer ligands that can be in a trianionic, protonated or protonated equivalent form. The ONO pincer ligand can be combined with a transition metal comprising compound to form an ONO pincer ligand comprising transition metal complex. By choice of the ONO pincer ligand structure, the steric and electronic properties of the transition metal complexes therefrom can be controlled. The ONO pincer ligands comprise a central nitrogen atom that is disubstituted with a pair of three atom comprising bridges where the three atoms are three sp 2  hybridized carbons or the three atoms are a pair of sp 2  hybridized carbons and an sp 3  hybridized carbon or silicon.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation-in-part of International PatentApplication No. PCT/US2012/037302, filed May 10, 2012, which claims thebenefit of U.S. Provisional Application Ser. No. 61/484,793, filed May11, 2011, the disclosures of which are hereby incorporated by referenceherein in their entirety, including any figures, tables, or drawings.

The subject invention was made with government support under theNational Science Foundation, Contract No. CHE-0748408. The governmenthas certain rights to this invention.

BACKGROUND OF INVENTION

Pincer ligands are chelating agents that bind metals tightly to threeadjacent coplanar sites. The pincer-metal interaction is rigid andtypically confers a high thermal stability to the ligand metalcomplexes. Organic portions and substituents define a hydrophobic pocketaround the coordination site. These ligands traditionally share thecommon feature of a central aromatic unit. To this central unit areattached, in the ortho positions, two arms whose electronic and stericproperties can be varied in many different ways. The ability to vary theproperties of pincer ligands has been exploited for numerous complexesto be used as catalysts. Early work mainly focused on ligands where thecentral binding site is carbon and the peripheral binding sites arephosphorous, generally referred to by the atomic symbols of the donoratoms at the binding sites as the PCP systems. More recently CCC, CNC,CNS, NNN, NCN, PNP, OCO, SCS, SNS have been reported. Most frequentlythe pincer ligand transition metal complexes have been those of groupVII-X metals where low coordinate and low oxidation state prevail andthe metals are tolerant of a wide variety of substituents.

Early transition metal (group III-VI) pincer complexes are significantlyless common and typically display high oxidation states and highcoordination numbers, are typically electrophilic, and are intolerant ofmany functional groups. As most presently known pincer ligands havemultiple soft donor atoms for metal binding, the ligands are not wellsuited to forming complexes with the early transition metals. Those thathave been prepared include: pincer dicarbene complexes of CNC ligandswith V, Ti, Cr, Mn, and Nb; nontraditional NNN ligands with Zr; NCNligands with W, Mo, Ti, La, Ta and Mn; and OCO ligands with Ti, Ta, andMo. The early transition metals form complexes with pincer type ligandswhere the donors are all considered hard donors. Although OCO pincerligands form transition metal complexes, the metal-carbon bond issusceptible to degradation via insertion reactions. Hence, pincerligands that are not readily susceptible to degradation but can bind togroup III through group X transition metals could be useful forcatalysts for a broad scope of reactions including N-atom transferreactions, aerobic oxidation, olefin polymerization, alkeneisomerization, and C—H bond activation.

BRIEF SUMMARY

Embodiments of the invention are directed to ONO pincer ligands in theirprotonated, partly protonated, or trianionic forms and the transitionmetal complexes comprising the ONO pincer ligands. The ligands share astructural feature of a central nitrogen atom connected via a pair ofbridges comprising three carbon atoms or two carbon atoms and a siliconatom to a pair of oxygen atoms where at least two of the carbon atomsare sp² hybridized. The two bridges can be of like structure ordifferent structure, and can include substituents to provide desiredsteric and electronic properties of transition metal complexescomprising the ONO pincer ligands.

Embodiments of the invention are directed to the preparation of the ONOpincer ligands. Other embodiments of the invention are directed to thepreparation of transition metal complexes comprising an ONO pincerligand.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a scheme for the synthesis of6,6′-(azanediylbis(methylene))bis(2-(tert-butyl)phenol) (4) according toan embodiment of the invention.

FIG. 2 is a scheme for the synthesis of2,2′-(azanediylbis(3-methyl-6,1-phenylene))bis(1,1,1,3,3,3-hexafluoro-propan-2-01)[F₆ONO]H₃ (5) according to an embodiment of the invention.

FIG. 3 is a ¹H NMR spectrum of 5 in CDCl₃.

FIG. 4 is a ¹⁹F{¹H} NMR spectrum of 5 in CDCl₃.

FIG. 5 is a ¹³C{¹H} NMR spectrum of 5 in CDCl₃.

FIG. 6 is a ¹³C {¹⁹F} NMR spectrum of 5 in CDCl₃.

FIG. 7 is a scheme for the synthesis of [F₆ONO]W—CHCH₂CH₃(O^(t)Bu) (6)according to an embodiment of the invention.

FIG. 8 is a ¹H NMR spectrum of 6 in CDCl₃.

FIG. 9 is a ¹⁹{¹H} NMR spectrum of 6 in CDCl₃.

FIG. 10 shows the solid state structure of 6 as determined by X-raycrystallography.

FIG. 11 is tabulated crystal data and structure refinement for 6.

FIG. 12 is tabulated atomic coordinates and equivalent isotropicdisplacement parameters for 6.

FIG. 13 is tabulated bond lengths and angles for 6.

FIG. 14 is tabulated anisotropic displacement parameters for 6.

FIG. 15 is a scheme for the synthesis of [^(t)BuOCH₂NHCH₂O]₂Mo (7)according to an embodiment of the invention.

FIG. 16 is a ¹H NMR spectrum of 7 in CDCl₃.

FIG. 17 shows the solid state structure of 7 with thermal ellipsoidsdrawn at the 50% probability level.

FIG. 18 is tabulated crystal data and structure refinement for 7.

FIG. 19 is tabulated atomic coordinates and equivalent isotropicdisplacement parameters for 7.

FIG. 20 is tabulated bond lengths and angles for 7.

FIG. 21 is a scheme for the synthesis of [^(t)BuOCH₂NHCH₂O]W≡CCH₂CH₃ (8)according to an embodiment of the invention.

FIG. 22 is a ¹H NMR spectrum of 8 in CDCl₃.

FIG. 23 shows the solid state structure of 8 with thermal ellipsoidsdrawn at the 50% probability level.

FIG. 24 is tabulated crystal data and structure refinement for 8.

FIG. 25 is tabulated atomic coordinates and equivalent isotropicdisplacement parameters for 8.

FIG. 26 is tabulated bond lengths and angles for 8.

FIG. 27 is tabulated anisotropic displacement parameters for 8.

FIG. 28 is a scheme for the synthesis of [CF₃—ONO]W(═CH^(t)Bu)(O^(t)Bu)(9) according to an embodiment of the invention.

FIG. 29 is a ¹H NMR spectrum of 9 in CDCl₃.

FIG. 30 is a ¹⁹F{¹H} NMR spectrum of 9 in CDCl₃.

FIG. 31 is a scheme for the synthesis of {H₃CPPh₃}{[CF₃—ONO]W(≡C^(t)Bu)(O^(t)Bu)} (10) according to an embodiment of theinvention.

FIG. 32 is a ¹H NMR spectrum of 10 in CDCl₃.

FIG. 33 is a scheme for the synthesis of{H₃CPPh₃}₂{[CF₃—ONO]W(≡C^(t)Bu)(OTf)₂} (11) according to an embodimentof the invention.

FIG. 34 is a ¹H NMR spectrum of 11 in CDCl₃.

FIG. 35 is a ¹⁹F{¹H} NMR spectrum of 11 in CDCl₃.

FIG. 36 is a scheme for the synthesis of [CF₃—ONO]W[C(^(t)Bu)C(Me)C(Ph)](12) according to an embodiment of the invention.

FIG. 37 is a ¹H NMR spectrum of 12 in C₆D₆.

FIG. 38 is a ¹⁹F{¹H} NMR spectrum of 12 in C₆D₆.

FIG. 39 is a ¹³C{¹H} NMR spectrum of 12 in C₆D₆.

FIG. 40 shows the solid state structure of 12 with thermal ellipsoidsdrawn at the 50% probability level.

FIG. 41 is tabulated crystal data and structure refinement for 12.

FIG. 42 is tabulated atomic coordinates and equivalent isotropicdisplacement parameters for 12.

FIG. 43 is tabulated bond lengths and angles for 12.

FIG. 44 is tabulated anisotropic displacement parameters for 12.

FIG. 45 is a scheme for the synthesis of6,6′-(1H-pyrrole-2,5-diyl)bis(2-(tert-butyl)phenol), [pyr-ONO]H₃ (14),according to an embodiment of the invention.

FIG. 46 is a scheme for the synthesis of [pyr-ONO]W═CH^(t)Bu(O^(t)Bu)(15), according to an embodiment of the invention, and, subsequently,{MePPh₃} {[pyr-ONO]W≡C^(t)Bu(O^(t)Bu)} (16), according to an embodimentof the invention.

FIG. 47 shows the solid state structure of 16 as determined by X-raycrystallography.

FIG. 48 is tabulated crystal data and structure refinement for 16.

FIG. 49 is tabulated atomic coordinates and equivalent isotropicdisplacement parameters for 16.

FIG. 50 is tabulated bond lengths for 16.

FIG. 51 is tabulated bond angles for 16.

FIG. 52 is tabulated anisotropic displacement parameters for 16.

DETAILED DISCLOSURE

Embodiments of the invention are directed to ONO pincer ligands: thetrianionic ONO pincer ligands; the protonated ONO ligand precursors; thetrianionic ONO pincer ligand comprising transition metal complexes;methods for the preparation of the precursors; and methods for thepreparation of the complexes. Modification of the ONO pincer ligandstructure allows the modification of the steric and electronicproperties of the transition metal complexes thereof. The trianionic ONOpincer ligands comprise a central nitrogen anion that is disubstitutedwith a pair of three carbon comprising bridges to terminal oxygenanions, or optionally a bridge comprising two carbons and one sp³silicon where the silicon is adjacent to the oxygen. Two adjacentcarbons of the bridge are sp² hybridized where a heteroatom, either thenitrogen or oxygen, is zusammen (cis) to the third carbon or the sp³silicon of the bridge, such that the anionic ONO pincer ligand canachieve, but are not necessarily restricted to, a conformation where theheteroatoms and bridging carbons are coplanar:

where X is C or Si.

Embodiments of the invention are described below where the two bridgesare identical in bridging structure, although the identity of thesubstituents can result in asymmetric ONO pincer ligands. The ONO pincerligands can be chiral or achiral. Other embodiments of the invention canhave non-identical bridges, and, as can be appreciated by one skilled inthe art, the bridge to the first oxygen can be of a different structurethan the bridge to the second oxygen. For example: one bridge cancomprise three sp² carbons and the other bridge can comprise two sp²carbons and one sp³ carbon; one bridge can be two sp² carbons and onesp³ carbon adjacent to the nitrogen and the other bridge can comprisetwo sp² carbons and an sp³ carbon adjacent to the oxygen; or thedifferent two bridges can include one bridge with the structure of anyof the embodiments below and the other bridge can include a bridge ofany second embodiment below.

The trianionic ONO pincer ligand comprising transition metal complexes,according to embodiments of the invention, can include group III throughgroup X transition metals. Embodiments of the invention are directed toONO pincer ligand comprising transition metal complexes where the metalsare early transition metals of group III through group VI. Thetrianionic ONO pincer ligand comprising transition metal complexes canbe used as catalysts. Depending on the structure of the trianionic ONOpincer ligand comprising transition metal complex, the catalysistherefrom can be used for N-atom transfer reactions, aerobic oxidation,olefin polymerization, alkene isomerization, olefin metathesis, alkynemetathesis, alkyne-nitrile cross metathesis, C—H bond activation, CO₂fixation, and dinitrogen fixation.

In an embodiment of the invention the trianionic ONO pincer ligandcomprises bridges with an sp² carbon adjacent to the oxygen and an sp³carbon adjacent to the nitrogen of the structure:

where R groups and R′ groups are independently H, C₁-C₃₀ alkyl, C₂-C₃₀alkenyl, C₂-C₃₀ alkynyl, C₆-C₁₄ aryl, C₇-C₃₀ arylalkyl, C₈-C₃₀arylalkenyl, C₈-C₃₀ arylalkynyl, C₁-C₃₀ alkoxy, C₆-C₁₄ aryloxy, C₇-C₃₀arylalkyloxy, C₂-C₃₀ alkenyloxy, C₂-C₃₀ alkynyloxy, C₈-C₃₀arylalkenyloxy, C₈-C₃₀ arylalkynyloxy, C₂-C₃₀ alkylester, C₇-C₁₅arylester, C₈-C₃₀ alkylarylester, C₃-C₃₀ alkenylester, C₃-C₃₀alkynylester, C₃-C₃₀ polyether, C₃-C₃₀ polyetherester, C₃-C₃₀ polyester,or where any of the R and R′ groups are perfluorinated, partiallyfluorinated, and/or otherwise substituted. Any alkyl group within thesubstituent can be linear, branched, cyclic, or any combination thereof.Alkenyl, alkynyl, ester, or ether functionality can be situated adjacentor remotely to the substituted carbon. Any of the R or R′ groups thatare not H can be further substituted with other functionality, forexample, a terminal alkene, alkyne, amino, hydroxy, trialkoxysilyl, orother group. The ONO pincer ligand can be covalently fixed to a polymer,polymeric network, a resin or other surface such as a glass or ceramic.In embodiments of the invention, any pair of R groups, any pair of R′groups, or any R and R′ groups of the same bridge can be combined intoany five to eight membered cyclic structure. For example, thesubstituted phenyl groups shown above can be part of a polycyclicaromatic where two R groups are an additional aromatic ring or rings.

In an embodiment of the invention, the R group ortho to the sp³ carbonof the bridge is connected to an R′ group of that sp³ carbon to form ananionic ONO pincer ligand of the structure:

where n is 0 to 2 and R and R′ are defined as above.

In an embodiment of the invention the trianionic ONO pincer ligandcomprises bridges with an sp² carbon adjacent to the nitrogen and an sp³carbon adjacent to the oxygen of the structure:

where R groups and R′ groups are independently H, C₁-C₃₀ alkyl, C₂-C₃₀alkenyl, C₂-C₃₀ alkynyl, C₆-C₁₄ aryl, C₇-C₃₀ arylalkyl, C₈-C₃₀arylalkenyl, C₈-C₃₀ arylalkynyl, C₁-C₃₀ alkoxy, C₆-C₁₄ aryloxy, C₇-C₃₀arylalkyloxy, C₂-C₃₀ alkenyloxy, C₂-C₃₀ alkynyloxy, C₈-C₃₀arylalkenyloxy, C₈-C₃₀ arylalkynyloxy, C₂-C₃₀ alkylester, C₇-C₁₅arylester, C₈-C₃₀ alkylarylester, C₃-C₃₀ alkenylester, C₃-C₃₀alkynylester, C₃-C₃₀ polyether, C₃-C₃₀ polyetherester, C₃-C₃₀ polyester,or where any of the R and R′ groups are perfluorinated, partiallyfluorinated, and/or otherwise substituted. Any alkyl group within thesubstituent can be linear, branched, cyclic, or any combination thereof.Alkenyl, alkynyl, ester, or ether functionality can be situated adjacentor remotely to the substituted carbon. Any of the R or R′ groups thatare not H can be further substituted with other functionality, forexample, a terminal alkene, alkyne, amino, hydroxy, trialkoxysilyl, orother group. The ONO pincer ligand can be covalently fixed to a polymer,polymeric network, a resin or other surface such as a glass or ceramic.In embodiments of the invention, any pair of R groups, any pair of R′groups, or any R and R′ groups of the same bridge can be combined intoany five to eight membered cyclic structure. For example, thesubstituted phenyl groups shown above can be part of a polycyclicaromatic where two R groups are an additional aromatic ring or rings.

An exemplary embodiment of a trianionic ONO pincer ligand that hasasymmetric bridges is a trianionic ONO pincer ligand of the structure:

where R and R′ are defined as above.

In an embodiment of the invention, the R group ortho to the sp³ carbonof the bridge is connected to an R′ group of that sp³ carbon to form ananionic ONO pincer ligand of the structure:

where n is 0 to 2 and R and R′ are defined as above. Where two R′ arecombined into a cyclic structure a bicycle structure can be formed, suchas:

In an embodiment of the invention the trianionic ONO pincer ligandcomprises bridges with an sp² carbon adjacent to the nitrogen and an sp³silicon adjacent to the oxygen of the structure:

where: R groups are independently H, C₁-C₃₀ alkyl, C₂-C₃₀ alkenyl,C₂-C₃₀ alkynyl, C₆-C₁₄ aryl, C₇-C₃₀ arylalkyl, C₈-C₃₀ arylalkenyl,C₈-C₃₀ arylalkynyl, C₁-C₃₀ alkoxy, C₆-C₁₄ aryloxy, C₇-C₃₀ arylalkyloxy,C₂-C₃₀ alkenyloxy. C₂-C₃₀ alkynyloxy. C₈-C₃₀ arylalkenyloxy, C₈-C₃₀arylalkynyloxy, C₂-C₃₀ alkylester, C₇-C₁₅ arylester, C₈-C₃₀alkylarylester, C₃-C₃₀ alkenylester, C₃-C₃₀ alkynylester, C₃-C₃₀polyether, C₃-C₃₀ polyetherester, or C₃-C₃₀ polyester, or where any ofthe R groups are perfluorinated, partially fluorinated, and/or otherwisesubstituted; and R′ groups are independently C₁-C₃₀ alkyl, C₂-C₃₀alkenyl, C₂-C₃₀ alkynyl, C₆-C₁₄ aryl, C₇-C₃₀ arylalkyl, C₈-C₃₀arylalkenyl, C₈-C₃₀ arylalkynyl, C₁-C₃₀ alkoxy, C₆-C₁₄ aryloxy, C₇-C₃₀arylalkyloxy, C₂-C₃₀ alkenyloxy, C₂-C₃₀ alkynyloxy, C₈-C₃₀arylalkenyloxy, C₈-C₃₀ arylalkynyloxy, or where any of the R′ groups arepartially fluorinated, and/or otherwise substituted. Any alkyl groupwithin the substituent can be linear, branched, cyclic, or anycombination thereof. Alkenyl, alkynyl, ester, or ether functionality canbe situated adjacent or remotely to the substituted carbon. Any of the Ror R′ groups that are not H can be further substituted withfunctionality, for example, a terminal alkene, alkyne, amino, hydroxy,trialkoxysilyl, or other group. The ONO pincer ligand can be covalentlyfixed to a polymer, polymeric network, a resin or other surface such asa glass or ceramic.

In an embodiment of the invention the trianionic ONO pincer ligandcomprises bridges with an sp² carbon adjacent to the nitrogen and on onebridge an sp³ silicon adjacent to the oxygen and on the other bridge ansp³ carbon adjacent to the oxygen of the structure:

where R groups and R′ groups attached to a carbon atom are independentlyH, C₁-C₃₀ alkyl, C₂-C₃₀ alkenyl, C₂-C₃₀ alkynyl, C₆-C₁₄ aryl, C₇-C₃₀arylalkyl, C₈-C₃₀ arylalkenyl, C₈-C₃₀ arylalkynyl, C₁-C₃₀ alkoxy, C₆-C₁₄aryloxy, C₇-C₃₀ arylalkyloxy, C₂-C₃₀ alkenyloxy, C₂-C₃₀ alkynyloxy,C₈-C₃₀ arylalkenyloxy, C₈-C₃₀ arylalkynyloxy, C₂-C₃₀ alkylester, C₇-C₁₅arylester, C₈-C₃₀ alkylarylester, C₃-C₃₀ alkenylester, C₃-C₃₀alkynylester, C₃-C₃₀ polyether, C₃-C₃₀ polyetherester, C₃-C₃₀ polyester,or where any of the R and R′ groups are perfluorinated, partiallyfluorinated, and/or otherwise substituted; and R′ groups attached to asilicon atom are independently C₁-C₃₀ alkyl, C₂-C₃₀ alkenyl, C₂-C₃₀alkynyl, C₆-C₁₄ aryl, C₇-C₃₀ arylalkyl, C₈-C₃₀ arylalkenyl, C₈-C₃₀arylalkynyl, alkoxy, C₆-C₁₄ aryloxy, C₇-C₃₀ arylalkyloxy, C₂-C₃₀alkenyloxy, C₂-C₃₀ alkynyloxy, C₈-C₃₀ arylalkenyloxy, C₈-C₃₀arylalkynyloxy, or where any of the R′ groups are partially fluorinated,and/or otherwise substituted or any combination thereof. Any alkyl groupwithin the substituent can be linear, branched, cyclic, or anycombination thereof. Alkenyl, alkynyl, ester, or ether functionality canbe situated adjacent or remotely to the substituted carbon. Any of the Ror R′ groups that are not H can be further substituted with a functionalgroup, for example, a terminal alkene, alkyne, amino, hydroxy,trialkoxysilyl, or other group. The ONO pincer ligand can be covalentlyfixed to a polymer, polymeric network, a resin or other surface such asa glass or ceramic.

In one embodiment of the invention, sp² hybridized carbons of the twobridges that are ortho to the nitrogen can be connected to form ananionic ONO pincer ligand of the structure:

where X groups are independently C or Si, m is 0 or 1, and R and R′ aredefined as above where X is C and where X is Si.

In an embodiment of the invention the trianionic ONO pincer ligandcomprises bridges with an sp² carbon adjacent to the nitrogen and an sp²carbon adjacent to the oxygen of the structure:

where R groups are independently H, C₁-C₃₀ alkyl, C₂-C₃₀ alkenyl, C₂-C₃₀alkynyl, C₆-C₁₄ aryl, C₇-C₃₀ arylalkyl, C₈-C₃₀ arylalkenyl, C₈-C₃₀arylalkynyl, C₁-C₃₀ alkoxy, C₆-C₁₄ aryloxy, C₇-C₃₀ arylalkyloxy, C₂-C₃₀alkenyloxy, C₂-C₃₀ alkynyloxy, C₈-C₃₀ arylalkenyloxy, C₈-C₃₀arylalkynyloxy, C₂-C₃₀ alkylester, C₇-C₁₅ arylester, C₈-C₃₀alkylarylester, C₃-C₃₀ alkenylester, C₃-C₃₀ alkynylester, C₃-C₃₀polyether, C₃-C₃₀ polyetherester, C₃-C₃₀ polyester, or where any of theR groups are perfluorinated, partially fluorinated, and/or otherwisesubstituted. Any alkyl group within the substituent can be linear,branched, cyclic, or any combination thereof Alkenyl, alkynyl, ester, orether functionality can be situated adjacent or remotely to thesubstituted carbon. Any of the R groups that are not H can be furthersubstituted with functionality, for example, a terminal alkene, alkyne,amino, hydroxy, trialkoxysilyl, or other group. The ONO pincer ligandcan be covalently fixed to a polymer, polymeric network, a resin orother surface such as a glass or ceramic. In embodiments of theinvention, any pair of R groups can be combined into any five to eightmembered cyclic structures.

In one embodiment of the invention, two sp² hybridized carbons of thetwo bridges that are ortho to the nitrogen can be connected to form ananionic ONO pincer ligand of the structure:

where m is 0 or 1, and R is defined as above and R′ is defined as abovewhen attached to a carbon atom.

In an embodiment of the invention the trianionic ONO pincer ligandcomprises bridges with an sp² carbon adjacent to the nitrogen and an sp²carbon adjacent to the oxygen of the structure:

where X′ groups are independently O or R″₂C; R groups are independentlyH, C₁-C₃₀ alkyl, C₂-C₃₀ alkenyl, C₂-C₃₀ alkynyl, C₆-C₁₄ aryl, C₇-C₃₀arylalkyl, C₈-C₃₀ arylalkenyl, C₈-C₃₀ arylalkynyl, C₁-C₃₀ alkoxy, C₆-C₁₄aryloxy, C₇-C₃₀ arylalkyloxy, C₂-C₃₀ alkenyloxy, C₂-C₃₀ alkynyloxy,C₈-C₃₀ arylalkenyloxy, C₈-C₃₀ arylalkynyloxy, C₂-C₃₀ alkylester, C₇-C₁₅arylester, C₈-C₃₀ alkylarylester, C₃-C₃₀ alkenylester, C₃-C₃₀alkynylester, C₃-C₃₀ polyether, C₃-C₃₀ polyetherester, or C₃-C₃₀polyester; and R″ groups are independently H, C₁-C₃₀ alkyl, C₂-C₃₀alkenyl, C₂-C₃₀ alkynyl, C₆-C₁₄ aryl, C₇-C₃₀ arylalkyl, C₈-C₃₀arylalkenyl, C₈-C₃₀ arylalkynyl, or where any of the R or R″ groups areperfluorinated, partially fluorinated, and/or otherwise substituted. Anyalkyl group within the substituent can be linear, branched, cyclic, orany combination thereof. Alkenyl, alkynyl, ester, or ether functionalitycan be situated adjacent or remotely to the substituted carbon. Any ofthe R groups that are not H can be further substituted withfunctionality, for example, a terminal alkene, alkyne, amino, hydroxy,trialkoxysilyl, or other group. The ONO pincer ligand can be covalentlyfixed to a polymer, polymeric network, a resin or other surface such asa glass or ceramic. In embodiments of the invention, any pair of Rgroups, R″ groups can be combined into any five to eight membered cyclicstructure.

In one embodiment of the invention, two sp² hybridized carbons of thetwo bridges that are ortho to the nitrogen can be connected to form atrianionic ONO pincer ligand of the structure:

where X′, m, R, R′, and R″ are defined as above where R′ is bonded tocarbon.

In an embodiment of the invention the trianionic ONO pincer ligandcomprises bridges with an sp² carbon adjacent to the nitrogen and an sp²carbon adjacent to the oxygen of the structure:

where X′ groups are independently O or R″₂C; R groups are independentlyH, C₁-C₃₀ alkyl, C₂-C₃₀ alkenyl, C₂-C₃₀ alkynyl, C₆-C₁₄ aryl, C₇-C₃₀arylalkyl, C₈-C₃₀ arylalkenyl, C₈-C₃₀ arylalkynyl, C₁-C₃₀ alkoxy, C₆-C₁₄aryloxy, C₇-C₃₀ arylalkyloxy, C₂-C₃₀ alkenyloxy, C₂-C₃₀ alkynyloxy,C₈-C₃₀ arylalkenyloxy, C₈-C₃₀ arylalkynyloxy, C₂-C₃₀ alkylester, C₇-C₁₅arylester, C₅-C₃₀ alkylarylester, C₃-C₃₀ alkenylester, C₃-C₃₀alkynylester, C₃-C₃₀ polyether, C₃-C₃₀ polyetherester, C₃-C₃₀ polyester,or where any of the R groups are perfluorinated, partially fluorinated,and/or otherwise substituted; and R″ groups are independently H, C₁-C₃₀alkyl, C₂-C₃₀ alkenyl, C₂-C₃₀ alkynyl, C₆-C₁₄ aryl, C₇-C₃₀ arylalkyl,C₈-C₃₀ arylalkenyl, C₈-C₃₀ arylalkynyl, or where any of the R″ groupsare perfluorinated, partially fluorinated, and/or otherwise substituted.Any alkyl group within the substituent can be linear, branched, cyclic,or any combination thereof. Alkenyl, alkynyl, ester, or etherfunctionality can be situated adjacent or remotely to the substitutedcarbon. Any of the R groups that are not H can be further substitutedwith functionality, for example, a terminal alkene, alkyne, amino,hydroxy, trialkoxysilyl, or other group. The ONO pincer ligand can becovalently fixed to a polymer, polymeric network, a resin or othersurface such as a glass or ceramic. In embodiments of the invention, anypair of R groups, R″ groups can be combined into any five to eightmembered cyclic structure, for example:

The trianionic ONO pincer ligands can be formed from their protonatedprecursors or from a precursor having a proton equivalent, for example,the nitrogen can be bonded to a silicon atom as a silazane or an activeamide, or, for example the oxygen can be part of an active ester orether, where the anionic oxygen and nitrogen can be readily formed byone or more reactions that gives the identical trianionic ONO pincerligand to that of deprotonation of a protonated precursor. Theprotonated precursors to the trianionic form of the ONO pincer ligandsshown above have the structures:

where X, X′. R, R′, R″, n and m are defined for the above equivalenttrianionic OCO pincer ligands. Where X′ is R″₂C and the beta heteroatomis oxygen, a ketone equivalent to the enol can be the predominate formof the protonated precursor prior to formation of the trianionic form ofthe ONO pincer ligand. Where X is Si, depending upon the nature of R′, asilanol species may not be sufficiently stable for long term storage,but can be generated from a trimethylsilyloxy, acetoxy, or other protonequivalent by nucleophilic substitution, for example, by a fluoride ionat a trimethylsilyloxy or water with an acetoxy, to form siloxide anionor the silanol, respectively, prior to or during the formation of atransition metal complex of the ONO pincer ligand.

Methods to prepare the ONO precursors are numerous, as can beappreciated by those skilled in the art. According to embodiments of theinvention, a nucleophilic oxygen or nucleophilic nitrogen compound arecondensed with an electrophilic carbon of a molecule comprising thebridge structure. In some embodiments of the invention, theelectrophilic carbon containing the bridge structure also contains theoxygen or the nitrogen that is not formed by reaction with thenucleophile, where that oxygen or nitrogen is protected prior to thenucleophilic reaction. Two exemplary embodiments of the methods ofpreparation of the precursor ONO pincer ligands are illustrated below.

Preparation of the trianionic ONO pincer ligand comprising metalcomplexes can be carried out according to an embodiment of theinvention, where a precursor metal compound comprising a metal alkoxideor metal amide allows formation of a trianionic ONO pincer ligandcomprising complex upon proton and ligand exchange between the alkoxideor amide of the metal alkoxide or metal amide and the anionic ONO pincerligand. In another embodiment of the method, a precursor metal compoundcomprises a metal oxide or metal amide and further comprises a metalalkylidyne wherein the ligand exchange is accompanied by OH or NHaddition across the metal alkylidyne to form the anionic ONO pincerligand comprising metal complexes. Three exemplary embodiment of themethod of preparation of the anionic ONO pincer ligand comprising metalcomplexes are illustrated below.

Methods and Materials

General Considerations.

Unless specified otherwise, all manipulations were performed under aninert atmosphere using standard Schlenk or glovebox techniques.Glassware was oven-dried before use. Pentane, hexanes, toluene, diethylether (Et₂O), tetrahydrofuran (THF), 1,2-dimethoxyethane (DME), andacetonitrile were dried using a GlassContours drying column. Benzene-d₆and toluene-d₈ (Cambridge Isotopes) were dried over sodium-benzophenoneketyl and distilled or vacuum transferred and stored over 4 Å molecularsieves. NMR spectra were obtained on Varian INOVA 500 MHz, VarianMercury Broad Band 300 MHz, or Varian Mercury 300 MHz spectrometers.Chemical shifts are reported in δ (ppm). For ¹H and ¹³C {¹H} NMRspectra, the solvent resonance was referenced as an internal reference.Accurate mass was determined by Atmospheric Pressure ChemicalIonization-Mass Spectrometric (APCI-MS) method in diluteddichloromethane solution, and the spectrum was recorded on an Agilent6210 TOF-MS. Elemental analyses were performed at Complete AnalysisLaboratory Inc., Parsippany, N.J.

Synthesis of 6,6′-(azanediylbis(methylene))bis(2-(tert-butyl)phenol) (4)

As indicated in the reaction scheme shown in FIG. 1, ortho-substitutedsalicylaldehyde (1) (1.8 g, 10.1 mmol) was treated with Nail or KH(12.12 mmol) in dry THF for one hour at room temperature followed by theaddition of excess methoxymethyl chloride (MOMCl) (30.3 mmol) viasyringe. Stirring the resulting reaction mixture overnight resulted inthe MOM protection aldehyde (2) as golden yellow oil after columnchromatographic purification (hexanes/ethyl acetate (80/20) in 80%yield. A slurry of the protected aldehyde (2) (1.5 g, 6.75 mmol),Ti(i-PrO)₄ (4 mL, 13.5 mmol), NH₄Cl (722 mg, 13.5 mmol) andtriethylamine (1.9 mL, 13.5 mmol) in absolute ethanol (25 mL) wasstirred under Ar in a capped flask at ambient temperature for 12 hours,after which NaBH₄ (383 mg, 10.13 mmol) was added and the resultingmixture was stirred for additional 7 hours at ambient temperature. Thereaction was quenched by pouring the mixture into an ammonium hydroxidesolution (2 M, 25 mL). The resulting precipitate was filtered, andwashed with ethyl acetate (2×25 mL). The organic layer was separated andthe remaining aqueous layer was extracted with ethyl acetate (2×25 mL).The combined organic extracts were dried over MgSO₄ and concentratedunder vacuum to obtain 3. Deprotection of the MOM ether was achieved bytreating 3 with 3 equivalents of HCl (1 M HCl solution in ether). Uponaddition of HCl a precipitate formed and subsequently was filtered,dried, and dissolved in CHCl₃. A NaOH solution (0.1 M) was added toneutralize the solution. The organic layer was removed and dried withMgSO₄ and volatiles were removed. The residue was redissolved in aminimal amount of CHCl₃. The solution was heated and added to coldhexanes to precipitate [^(t)BuOCH₂NCH₂O]H₃ (4) as a whitemicrocrystalline solid (yield=16%). ESI-MS: Calc. for [C₂₂H₃₂N₁O₄]⁺: m/z342.24 [4+H⁺]. Found m/z 342.2.

¹H NMR data of (2): ¹H NMR (300 MHz, CDCl₃), δ (ppm): 10.23 (s, 1H,CHO), 7.74-7.71 (dd, J=7.63 Hz, 1H, Ar—H), 7.63-7.59 (dd, J=7.93 Hz, 1H,Ar—H), 7.18 (t, J=7.63, 1H, Ar—H), 5.05 (s, 21-1, —OCH₂OCH₃), 3.65 (s,3H, —OCH₂OCH₃), 1.44 (s, 9H, —C(CH₃)₃).

¹HNMR data of (3): ¹H NMR (300 MHz, CDCl₃), δ (ppm): 7.28 (s, 2H, Ar—H),7.26 (s, 2H, Ar—H), 7.03 (t, J=7.63, 2H, Ar—H), 5.04 (s, 4H, OCH₂OCH₃),3.89 (s, 4H, Ar—CH₂) 3.59 (s, 6H, OCH₂OCH₃), 1.42 (s, 18H, —C(CH₃)₃).

NMR data of (4): ¹H NMR (300 MHz, CDCl₃), δ (ppm): 7.26-7.23 (dd,J=7.93, 2H, Ar—H), 6.99-6.96 (dd, J=7.32, 2H, Ar—H), 6.81 (t, J=7.63,2H, Ar—H), 3.94 (s, 4H, Ar—CH₂), 1.44 (s, 18H, —C(CH₃)₃). ¹³C{¹H} NMR(75.36 Hz, C₆D₆), δ (ppm): 155.29 (s, 2C, Ar), 136.93 (s, 2C, Ar),127.94 (s, 2C, Ar), 126.75 (s, 2C, Ar), 123.75 (s, 2C, Ar), 119.63 (s,2C, Ar), 51.20 (s, CH₂), 34.78 (s, —C(CH₃)₃), 29.95 (s, —C(CH₃)₃).

Synthesis of2,2′-(azanediylbis(3-methyl-6,1-phenylene))bis(1,1,1,3,3,3-hexafluoro-propan-2-ol)[F₆ONO]H₃ (5)

As indicated in the reaction scheme shown in FIG. 2, in anitrogen-filled glovebox an n-butyl-lithium solution (10.9 mL, 2.5 M,27.3 mmol) was added dropwise to a Schlenk-flask containing a −35° C.solution of bis(2-bromo-4-methylphenyl)amine (3.103 g, 8.79 mmol) indiethyl ether (30 mL). The reaction mixture was stirred for two hourswhile warming to room temperature. The reaction flask was fitted with adry-ice condenser before exiting the box. The reaction solution wascooled to −78° C., and dry-ice and acetone was added to the condenser.Hexafluoroacetone was condensed into a pressure flask at −78° C. (5 mL,6.6 g, 39 mmol) prior to addition to the reaction flask.Hexafluoroacetone evaporates slowly and condenses into the reactionflask via the side-arm of the Schlenk flask. The reaction mixture wasallowed to warm to room temperature and stirred for 3 hrs until theexcess hexafluoroacetone evaporates. The addition of HCl in Et₂O (27.3mL, 1 M) precipitates lithium chloride from a red solution. The solutionwas filtered and the filtrate was reduced to a thick oil. The thick oilwas placed under vacuum for two hours; then adding hexanes precipitatedthe product 5 as a pinkish-white powder (1.66 g, 35% yield). NMR (CDCl₃)(shown in FIG. 3): δ=7.5-7.0 (br, 3H, NH and 2 OH), 7.37 (s, 2H, Ar),7.17 (d, 2H, ³J=8.35 Hz, Ar), 8.83 (d, 2H, ³J=8.35 Hz, Ar), and 2.36 (s,3H, CH₃) ppm. ¹⁹F{¹H} NMR (CDCl₃) (shown in FIG. 4): δ=−74.9 (br) and−76.3 (br) ppm. ¹³C{¹H}NMR (CDCl₃) (shown in FIG. 5): δ=142.8 (s, Ar C),134.3 (s, Ar C), 132.1 (s, Ar C), 128.5 (s, Ar C), 126.0, (s, Ar C),120.8, (s, Ar CH), and 21.0 (s, CH₃) ppm. ¹³C{¹⁹F}NMR (CDCl3) (shown inFIG. 6): δ=122.8 (s, CF₃) and 80.3 (s, (CF₃)COH) ppm. Anal. Calcd. forC₂₀H₁₅F₁₂NO₂ (529.32 g/mole): C, 45.38; H, 2.86; N, 2.65. ESI-MS:530.0984 [5+H]⁺, 552.0803 [5+Na]⁺, and 574.0623 [5−H+2Na]⁺.

Synthesis of [F₆ONO]W═CHCH₂CH₃(O^(t)Bu) (6)

As indicated in the reaction scheme shown in FIG. 7, a benzene solution(5 mL) of [F₆ONO]H₃ (5) and (^(t)BuO)₃W≡CCH₂CH₃ were combined andstirred for 0.5 h after which volatiles were removed in vacuo. ¹H NMR(C₆D₆) (shown in FIG. 8): δ=7.72 (s, 2H, Ar), 7.36 (t, 1H, ³J=7.64 Hz,WCHCH₂CH₃), 6.81 (d, 1H, ³J=8.49 Hz, Ar), 6.66 (d, 1H, ³J=8.21 Hz, Ar),6.60 (d, 1H, ³J=9.06 Hz, Ar), 6.59 (d, 1H, ³J=8.49 Hz, Ar), 5.08 (ddq,1H, ²J=15.0 Hz, ³J=7.36 Hz, ³J=7.36 Hz, WCHC(H)(H)CH₃), 5.08 (ddq, 1H,²J=15.0 Hz, ³J=7.36 Hz, ³J=7.36 Hz, WCHC(H′)(H)CH₃), 4.79 (ddq, 1H,²J=15.0 Hz, ³J=7.64 Hz, ³J=7.64 Hz, WCHC(H′)(H)CH₃), 2.00 (s, 3H, CH₃′),1.96 (s, 3H, CH₃), 1.21 (s, 9H, OC(CH₃)₃, and 0.77 (t, ³J=7.36 Hz,WCHCH₂CH₃) ppm. ¹⁹F{¹H} NMR (C₆D₆) (shown in FIG. 9): δ=71.2 (qt., 3F,⁴J=9.61 Hz), 71.5 (qt., 3F, ⁴J=12.0 Hz), 73.9 (qt., 3F, ⁴J=9.60 Hz), and77.2 (qt., 3F, ⁴J=9.61 Hz) ppm. ¹³C{¹H} NMR (C₆D₆): δ=112.5 (s, Ar),111.8 (s, Ar), 104.1 (s, Ar), 103.7 (s, Ar), 102.6 (s, Ar), 101.6 (s,Ar), 99.6 (s, Ar), 98.7 (s, Ar), 98.3 (br, Ar), 96.6 (s, Ar), 96.5 (s,Ar), 96.3 (s, Ar), 90.7 (s, OCMe₃), 33.6 (s, WCHCH₂CH₃), 29.8 (s,OC(CH₃)₃), 21.4 (s, WCHCH₂CH₃), 21.0 (s, CH₃′), and 20.8 (s, CH₃) ppm.

X-Ray Experimental for 6:

X-Ray Intensity data were collected at 100 K on a Bruker SMARTdiffractometer using MoKα radiation (λ=0.71073 Å) and an APEXII CCD areadetector. Raw data frames were read by program SAINT and integratedusing 3D profiling algorithms. The resulting data were reduced toproduce hkl reflections and their intensities and estimated standarddeviations. The data were corrected for Lorentz and polarization effectsand numerical absorption corrections were applied based on indexed andmeasured faces. The structure (shown in FIG. 10) was solved and refinedin SHELXTL6.1, using full-matrix least-squares refinement. The non-Hatoms were refined with anisotropic thermal parameters and all of the Hatoms were calculated in idealized positions and refined riding on theirparent atoms. A disorder between H4a and a small percentage of Br on C4was identified with the final refinement yielding 3% of Br and 97% ofthe proton. The Br atom was refined with several site occupation factorsuntil an acceptable value was reached; which was 3%. In the final cycleof refinement, 5441 reflections (of which 4758 are observed withI>2σ(I)) were used to refine 403 parameters and the resulting R₁, wR₂and S (goodness of fit) were 2.51%, 4.76% and 1.050, respectively. Therefinement was carried out by minimizing the wR₂ function using F²rather than F values. R₁ is calculated to provide a reference to theconventional R value but its function is not minimized. SHELXTL6 (2000).Bruker-AXS, Madison, Wis., USA. FIG. 11 gives the crystal data andstructure refinement for 6. FIG. 12 gives atomic coordinates andequivalent isotropic displacement parameters for 6. FIG. 13 gives bondlengths and angles for 6. FIG. 14 gives anisotropic displacementparameters for 6.

Synthesis of [^(t)BuOCH₂NHCH₂O]₂Mo (7)

As indicated in the reaction scheme shown in FIG. 15, to a cold THFsolution of [^(t)BuOCH₂NHCH₂O]H₃ (4) (51.2 mg, 0.15 mmol) was addeddropwise a cold THF solution of molybdenum tetrakisdimethylamide(Mo(NMe₂)₄) (40.8 mg, 0.15 mmol) and the resulting solution was stirredfor 30 minutes. The solvent was removed and the resulting residue wastriturated with pentane and dried under vacuum. FIG. 16 shows a ¹H NMRspectrum of 7 in CDCl₃. Single crystals were grown by cooling aconcentrated ether solution of the 7.

X-Ray Experimental for 7:

X-Ray Intensity data were collected at 100 K on a Bruker DUOdiffractometer using MoKα radiation (λ=0.71073 Å) and an APEXII CCD areadetector. Raw data frames were read by program SAINT¹ and integratedusing 3D profiling algorithms. The resulting data were reduced toproduce hkl reflections and their intensities and estimated standarddeviations. The data were corrected for Lorentz and polarization effectsand numerical absorption corrections were applied based on indexed andmeasured faces. The structure (shown in FIG. 17) was solved and refinedin SHELXTL6.1, using full-matrix least-squares refinement. The non-Hatoms were refined with anisotropic thermal parameters and all of the Hatoms were calculated in idealized positions and refined riding on theirparent atoms. The asymmetric unit consists of the Mo complex and twoether solvent molecules in general positions. The latter were disorderedand could not be modeled properly; thus program SQUEEZE, a part of thePLATON package of crystallographic software, was used to calculate thesolvent disorder area and remove its contribution to the overallintensity data. In the final cycle of refinement, 11917 reflections (ofwhich 5649 are observed with I>2σ(I)) were used to refine 472 parametersand the resulting R₁, wR₂ and S (goodness of fit) were 5.90%, 13.22% and0.729, respectively. The refinement was carried out by minimizing thewR₂ function using F² rather than F values. R₁ is calculated to providea reference to the conventional R value but its function is notminimized. FIG. 13 shows the solid state structure of 7 with thermalellipsoids drawn at the 50% probability level. FIG. 18 give the crystaldata and structure refinement for 7. FIG. 19 gives atomic coordinatesand equivalent isotropic displacement parameters for 7. FIG. 20 givesbond lengths and angles for 7. FIG. 21 gives anisotropic displacementparameters for 7.

In situ generation of [^(t)BuOCH₂NHCH₂O]W≡CCH₂CH₃ (8).

As indicated in the reaction scheme shown in FIG. 21, A J-Young tube wascharged with the ligand precursor [^(t)BuOCH₂NCH₂O]H₃ (4) (7.85 mg,0.023 mmol) and (^(t)BuO)₃W≡CCH₂CH₃ (10.2 mg, 0.023 mmol). Upondissolving the alkylidyne, complex 8 forms. FIG. 22 shows a ¹H NMRspectrum of 8 in CDCl₃.

X-RAY Experimental for 8:

X-Ray Intensity data were collected at 100 K on a Bruker DUOdiffractometer using MoKα radiation (λ=0.71073 Å) and an APEXII CCD areadetector. Raw data frames were read by program SAINT¹ and integratedusing 3D profiling algorithms. The resulting data were reduced toproduce hkl reflections and their intensities and estimated standarddeviations. The data were corrected for Lorentz and polarization effectsand numerical absorption corrections were applied based on indexed andmeasured faces. The structure (shown in FIG. 23) was solved and refinedin SHELXTL6.1, using full-matrix least-squares refinement. The non-Hatoms were refined with anisotropic thermal parameters and all of the Hatoms were calculated in idealized positions and refined riding on theirparent atoms. The asymmetric unit consists of the Mo complex and twoether solvent molecules in general positions. The latter were disorderedand could not be modeled properly; thus program SQUEEZE, a part of thePLATON package of crystallographic software, was used to calculate thesolvent disorder area and remove its contribution to the overallintensity data. In the final cycle of refinement, 11917 reflections (ofwhich 5649 are observed with I>2σ(I)) were used to refine 472 parametersand the resulting R₁, wR₂ and S (goodness of fit) were 5.90%, 13.22% and0.729, respectively. The refinement was carried out by minimizing thewR₂ function using F² rather than F values. R₁ is calculated to providea reference to the conventional R value but its function is notminimized. FIG. 24 gives the crystal data and structure refinement for8. FIG. 25 gives atomic coordinates and equivalent isotropicdisplacement parameters for 8. FIG. 26 gives bond lengths and angles for8. FIG. 27 gives anisotropic displacement parameters for 8.

Synthesis of [CF₃—ONO]W(═CH^(t)Bu)(O^(t)Bu) (9)

As indicated in the reaction scheme shown in FIG. 28, to 2 mL of(^(t)BuO)₃W≡C^(t)Bu (0.289 g, 6.11×10⁻⁴ mol) in benzene was added 2 mLof H₃[CF₃—ONO] (1) (0.324 g, 6.11×10⁻⁴ mol) in benzene dropwise. Thereaction mixture was stirred for 1 hour then dried under vacuum for 4hours to yield a brown powder. The solid residue was dissolved inpentane (10 mL) and filtered. Cooling the filtrate to −35° C. yieldedcrystals of 9. Subsequently concentrating the filtrate via vacuum andcooling yielded more crystals of 9. The combined yield is 0.350 g (66%).¹H NMR (C₆D₆) (shown in FIG. 29): δ=7.71 (s, 1H, Ar—H), 7.69 (s, 1H,Ar—H), 6.81 (d, 1H, Ar—H, ³J=8.21 Hz), 6.66 (d, 1H, Ar—H, ³J=8.50 Hz),6.57 (d, 2H, Ar—H, ³J=8.50 Hz), 6.44 (s, 1H, W═CH^(t)Bu, satellites²J(¹H, ¹⁸³W)=8.80 Hz), 1.99 (s, 3H, Ar—CH₃), 1.94 (s, 3H, Ar—CH₃′), 1.24(s, 9H, —OC(CH₃)₃), 1.15 (s, 9H, W═CHC(CH₃)₃) ppm. ¹⁹F{¹H} NMR (C₆D₆)(shown in FIG. 30): δ=−70.71 (q, 3F, ⁴J=8.48 Hz), −71.52 (q, 3F,⁴J=10.90 Hz), −73.44 (q, 3F, ⁴J=10.90 Hz), −77.31 (q, 3F, ⁴J=8.48 Hz)ppm. ¹³C{¹H} NMR (C₆D₆, 500 MHz): δ=262.6 (s, W═CH^(t)Bu), 146.5 (s,Ar—C), 145.4 (s, Ar—C), 134.4 (s, Ar—C), 133.6 (s, Ar—C), 133.0 (s,Ar—C), 131.0 (s, Ar—C), 127.5 (s, Ar—C), 127.3 (s, Ar—C), 126.2 (s,Ar—C), 124.6 (m, CF₃), 124.3 (m, CF₃), 123.9 (s, Ar—C), 123.7 (m, CF₃),123.5 (s, Ar—C), 90.4 (s, —OC(CH₃)₃), 84.3 (m, —C(CF₃)₂), 82.8 (m,—C(CF₃)₂), 41.0 (s, W═CHC(CH₃)₃), 35.0 (s, W═CHC(CH₃)₃), 29.2 (s,—OC(CH₃)₃), 20.3 (s, Ar—CH₃), 20.1 (s, Ar—CH₃′) ppm. Anal. Calcd. forC₃₀H₃₃F₁₂NO₃W (867.18 g/mol): C, 41.54%; H, 3.83%; N, 1.61%. Found; C,41.42%; H, 3.73; N, 1.59%.

Synthesis of {H₃CPPh₃}{[CF₃—ONO]W(≡C^(t)Bu)(O^(t)Bu)} (10)

As indicated in the reaction scheme shown in FIG. 31, to 3 mL 10 inpentane (0.277 g, 3.18×10⁻⁴ mol) was added 4 ml, of PPh₃CH₂ in pentane(0.088 g, 3.18×10⁻⁴ mol) dropwise. The product 10 precipitates fromsolution as an orange powder. The reaction mixture was stirred for 4hours before the orange powder was filtered from the solution and driedunder vacuum for 1 hour. The isolated yield was 0.228 g (80%). ¹H NMR(C₆D₆): δ=7.76 (s, 1H, Ar—H), 7.61 (s, 1H, Ar—H), 7.47 (d, 1H, Ar—H,³J=8.49 Hz), 6.95-7.15 (m, 16H, Ar—H), 6.92 (d, 1H, Ar—H, ³J=8.49 Hz),6.75 (d, 1H, Ar—H, ³J=8.49 Hz), 2.36 (d, 3H, Ph₃PCH₃, ²J=13.31 Hz), 2.14(s, 311, Ar—CH₃), 2.06 (s, 3H, Ar—CH₃′), 1.66 (s, 9H, —OC(CH₃)₃), and1.17 (s, 9H, W═CHC(CH₃)₃) ppm. ¹⁹F{¹H} NMR (C₆D₆) (shown in FIG. 35):δ=−68.67 (q, 3F, ⁴J=9.61 Hz), −71.19 (q, 3F, ⁴J=9.61 Hz), −74.39 (q, 3F,⁴J=9.61 Hz), −76.20 (q, 3F, ⁴J=9.61 Hz). ³¹P{¹H} NMR (C₆D₆): δ=−21.6ppm. ¹³C{¹H} NMR (C₆D₆, 500 MHz): δ=286.0 (s, W≡C^(t)Bu), 155.5 (s,Ar—C), 154.5 (s, Ar—C), 131.5 (s, Ar—C), 130.3 (s, Ar—C), 130.2 (s,Ar—C), 127.8 (s, Ar—C), 127.2 (s, Ar—C), 127.0 (s, Ar—C), 126.2 (s,Ar—C), 122.9 (s, Ar—C), 122.6 (s, Ar—C), 121.0 (s, Ar—C), 85.4 (m,—C(CF₃)₂), 83.6 (m, —C(CF₃)₂), 77.1 (s, —OC(CH₃)₃), 49.4 (s,W≡CC(CH₃)₃), 33.7 (s, W≡CC(CH₃)₃), 33.5 (s, —OC(CH₃)₃), 20.7 (s,Ar—CH₃), 20.5 (s, Ar—CH₃′) ppm. Anal. Calcd. for C₄₈H₄₈F₁₂NO₃PW (1129.27g/mol): C, 51.03%; H, 4.28%; N, 1.24%. Found; C, 50.98%; H, 4.38; N,1.18%.

Synthesis of {H₃CPPh₃}₂{[CF₃—ONO]W(≡C^(t)Bu)(OTf)₂} (11)

As indicated in the reaction scheme shown in FIG. 33, to a benzenesolution (2 mL) of 11 (0.125 g, 1.11×10⁻⁴ mol) was added MeOTf (0.018 g,1.11×10⁻⁴ mol). The reaction mixture was stirred overnight, turning froma red solution to a deep blue solution. The solvent was stripped to aresidual oil to which a minimal amount of benzene was added. Blue oilformed upon addition of hexanes to the benzene solution. The solvent wasdecanted and the oil dried under vacuum. ¹H NMR (C₆D₆) (shown in FIG.34): δ=7.79 (s, 1H, Ar—H), 7.66 (s, 1H, Ar—H), 7.30 (d, 1H, Ar—H,³J=8.21 Hz), 7.10-7.20 (br, 30H, (C₆H₅)₃PCH₃), 6.94 (d, 1H, Ar—H,³J=8.50 Hz), 6.87 (d, 1H, Ar—H, ³J=8.21 Hz), 6.77 (d, 1H, Ar—H, ³J=8.50Hz), 2.37 (d, 1H, Ph₃PCH₃, ²J=13.19 Hz), 2.07 (s, 1H, Ar—CH₃), 2.04 (s,1H, Ar—CH₃′), 1.05 (s, 9H, WCC(CH₃)₃) ppm. ¹⁹F{¹H} NMR (C₆D₆) (shown inFIG. 35): δ=−68.97 (q, 3F, ⁴J=8.48 Hz), −73.14 (q, 3F, ⁴J=8.48 Hz),−73.94 (q, 3F, ⁴J=9.69 Hz), −76.64 (q, 3F, ⁴J=9.69 Hz), −76.65 (s, 3F,—OSO₂CF₃), −78.18 (s, 3F, —OSO₂CF₃) ppm.

Synthesis of [CF₃—ONO]W[C(^(t)Bu)C(Me)C(Ph)] (12)

As indicated in the reaction scheme shown in FIG. 36, a diethyl ethersolution (3 mL) containing 9 (0.139 g, 1.23×10⁻⁴ mol), MeOTf (0.020 g,1.23×10⁻⁴ mol) and PhC≡CCH₃ (0.014 g, 1.23×10⁻⁴ mol) was prepared andstirred overnight. The solution was filtered and the filtrate reducedunder vacuum. The residue was dissolved in pentane, filtered, andreduced to a solid residue. The solid residue was rinsed with pentane.The solid residue was dissolved in Et₂O and slow evaporated to yieldcrystals of 12 (0.038 g). Additionally, the slow evaporation of pentanewashings yielded crystals of 12 (0.020 g) for an overall yield of 51%.Crystals suitable for single crystal X-ray diffraction were grown byslow evaporation of a pentane solution of 12. ¹H NMR (C₆D₆, 500 MHz)(shown in FIG. 37): δ=7.62 (s, 1H, Ar—H), 7.61 (s, 1H, Ar—H), 7.12 (t,2H, Ar—H, ³J=7.55 Hz), 7.08 (d, 1H, Ar—H, ³J=8.37 Hz), 7.02-7.05 (m, 3H,Ar—H), 6.90 (d, 1H, ³J=7.55 Hz), 6.87 (d, 1H¹³J=8.10 Hz), 6.80 (d,1H¹³J=8.37 Hz), 2.76 (s, 3H, WC₃(CH₃)), 2.00 (s, 3H, Ar—CH₃), 1.98 (s,3H, Ar—CH₃′), 1.18 (s, 9H, WC₃C(CH₃)₃) ppm. ¹⁹F{¹H} NMR (C₆D₆, 300 MHz)(shown if FIG. 38): δ=−71.49 (q, 3F, ⁴J=9.69 Hz), −72.07 (q, 3F, ⁴J=9.69Hz), −76.06 (q, 3F, ⁴J=9.69 Hz), −76.53 (q, 3F, ⁴J=9.69 Hz) ppm. ¹³C{¹H}NMR (C₆D₆, 500 MHz) (shown in FIG. 39): δ=245.37 (s, W═C), 243.03 (s,W═C), 146.76 (s, Ar—C), 145.61 (s, Ar—C), 138.94 (s, Ar—C), 133.16 (s,Ar—C), 132.69 (s, Ar—C), 130.68 (s, Ar—C), 129.94 (s, Ar—C), 128.99 (s,Ar—C), 128.68 (s, Ar—C), 127.84 (s, Ar—C), 126.45 (s, Ar—C), 66.26 (s,WC₃C(CH₃)₃), 43.03 (s, WC₃CH₃), 30.95 (s, WC₃C(CH₃)₃), 21.10 (s,Ar—CH₃), 16.36 (s, Ar—CH₃″) ppm. Anal. Calcd. for C₃₅H₃₁F₁₂NO₂W (909.45g/mol): C, 46.22%; H, 3.44%; N, 1.54%. Found; C, 46.31%; H, 3.50; N,1.60%.

X-Ray Experimental for 12:

X-Ray Intensity data were collected at 100 K on a Bruker DUOdiffractometer using MoKα radiation (λ=0.71073 Å) and an APEXII CCD areadetector. Raw data frames were read by program SAINT¹ and integratedusing 3D profiling algorithms. The resulting data were reduced toproduce hkl reflections and their intensities and estimated standarddeviations. The data were corrected for Lorentz and polarization effectsand numerical absorption corrections were applied based on indexed andmeasured faces. The structure (shown in FIG. 40) was solved and refinedin SHELXTL6.1, using full-matrix least-squares refinement. The non-Hatoms were refined with anisotropic thermal parameters and all of the Hatoms were calculated in idealized positions and refined riding on theirparent atoms. In the final cycle of refinement, 7644 reflections (ofwhich 6905 are observed with I>2σ(I)) were used to refine 457 parametersand the resulting R₁, wR₂ and S (goodness of fit) were 1.45%, 3.69% and1.051, respectively. The refinement was carried out by minimizing thewR₂ function using F² rather than F values. R₁ is calculated to providea reference to the conventional R value but its function is notminimized. A toluene molecule was disordered and could not be modeledproperly; thus program SQUEEZE, a part of the PLATON package ofcrystallographic software, was used to calculate the solvent disorderarea and remove its contribution to the overall intensity data. FIG. 41give the crystal data and structure refinement for 12. FIG. 42 givesatomic coordinates and equivalent isotropic displacement parameters for12. FIG. 43 gives bond lengths and angles for 12. FIG. 44 givesanisotropic displacement parameters for 12.

Synthesis of 2,5-bis(3-(tert-butyl)-2-methoxyphenyl)-1H-pyrrole,[pyr-ONO]Me₂ (13)

As indicated in FIG. 45, in an argon-filled glove box, a toluenesolution (15 mL) containing (3-(tert-butyl)-2-methoxyphenyl)boronic acid(0.660 g, 3.17×10⁻³ mol, 2.3 equiv),tetrakis(triphenylphosphine)-palladium(0) (0.159 g, 1.38×10⁻⁴ mol, 0.10equiv), Na₂CO₃ (1.16 g, 1.09×10⁻² mol, 7.9 equiv), KCl (0.308 g,4.13×10⁻³ mol, 3 equiv), andtert-butyl-2,5-dibromo-1H-pyrrole-1-carboxylate (0.448 g, 1.38×10⁻³ mol,1 equiv) was prepared. The reaction flask was fitted with a Liebigcondenser and Y-adapter prior to exiting the glovebox and attached to anargon Schlenk line. Under counter argon pressure, 15 mL of degassedethanol-water (2:1) solution was added to the reaction flask. Thereaction mixture was heated at 96° C. with stirring for 20 h, and duringthat time the solution changed from yellow to orange-red color. Thereaction mixture was allowed to cool, and then solvent was removed underreduced pressure. The residue was dissolved in CH₂Cl₂ (15 mL) and washedwith water and brine. The organic layer was dried with MgSO₄, and thesolvent was removed under reduced pressure. To the residue, 20 mL ofhexanes was added to precipitate a white solid. The mixture was stirredfor 0.5 h before filtering off the white solid. The collected filtratewas reduced under vacuum to yield an orange oil containing the BOCprotected pyrrole. The BOC protecting group is easily removed uponstirring the residue with 10 mL of 4 M HCl in 1,4-dioxane at 45° C. for18 h. The solvent was removed under reduced pressure. The residue wasdissolved in CH₂Cl), washed with saturated Na₂CO₃, and then water. Theorganic layer was dried with MgSO₄ prior to removing the solvent underreduced pressure. The purple oily residue was dissolved in minimal2-propanol (5 mL). Cooling the 2-propanol solution precipitates crystalsof the product, 2,5-bis(3-(tert-butyl)-2-methoxyphenyl)-1H-pyrrole(Yield=0.219 g, 47%). ¹H NMR (CDCl₃, 500 MHz): δ=9.90 (b, 1H, NH), 7.42(dd, 2H, ³J=7.6 Hz, ⁴J=1.7 Hz, Ar—H), 7.24 (dd, 2H, ³J=7.9 Hz, ⁴J=1.7Hz, Ar—H), 7.07 (t, 2H, ³J=7.8 Hz, Ar—H), 6.55 (d, 2H, ⁴J=2.7 Hz,Pyr-H), 3.57 (s, 6H, —OCH₃), 1.46 (s, 18H, —C(CH₃)₃) ppm. ¹³C{¹H} NMR(CDCl₃, 126 MHz): δ=156.3 (s, Ar C), 143.4 (s, Ar C), 130.0 (s, Ar C),127.4 (s, Ar C), 126.9 (s, Pyr C), 125.5 (s, Ar C), 123.8 (s, Ar C),108.1 (s, Pyr C), 60.8 (s, —OCH₃), 35.2 (s, —C(CH₃)₃), 31.0 (s,—C(CH₃)₃) ppm. Anal. Calcd. for C₂₆H₃₃NO₂: C, 79.76%; H, 8.50%; N,3.58%. Found; C, 79.35%; H: 8.11%; N, 3.79%.

Synthesis of 6,6′-(1H-pyrrole-2,5-diyl)bis(2-(tert-butyl)phenol),[pyr-ONO]H₃ (14)

As indicated in FIG. 45, in a glovebox, a 250 mL two-neck flask equippedwith a stirbar, condenser, and Y-adapter was charged with2-(diethylamino)ethanethiol hydrochloride (0.867 g, 6.12×10⁻³ mol, 2.4equiv) and NaO^(t)Bu (1.24 g, 1.29×10⁻² mol, 5.0 equiv). The apparatuswas brought out of the glovebox, attached to a Schlenk line, and cooledwith an ice-water bath. Anhydrous DMF (10 mL), which was also cooled inan ice-water bath, was added to the reaction flask. After 5 min, thereaction mixture was allowed to warm to room temperature. After stirringfor additional 15 min, 2,5-bis(3-(tert-butyl)-2-ethoxyphenyl)-1H-pyrrole(1.00 g, 2.55×10⁻³ mol, 1.0 equiv) was added in one portion undercounter argon flow, and the reaction mixture was refluxed for 3 h. Themixture was allowed to cool to ambient temperature, and then placed inan ice-water bath. Under counter argon flow, the reaction mixture wasneutralized by adding 1 M HCl drop-wise until the pH reaches 1.0, andthen diluted with water (25 mL). The aqueous phase was extracted withethyl acetate (3×25 mL). The combined organic extracts were washed withwater (3×10 mL), saturated brine solution (10 mL), and then dried overMgSO₄. The solvent was removed under vacuum to give a brown oil that wasrecrystallized from cold pentane to afford a beige microcrystallinepowder (Yield=0.34 g, 36%). ¹H NMR (CDCl₃, 500 MHz) δ (ppm): 8.98 (br,1H, NB), 7.25 (d, 4H, ³J=7.60 Hz, Ar—H), 6.92 (t, 2H, ³J=7.60 Hz, Ar—H),6.57 (d, 2H, ⁴J=5.78 Hz, Pyr-H), 6.12 (s, 2H, —OH), 1.46 (s, 18H,C(CH₃)₃). ¹³C{¹H} NMR (CDCl₃, 126 MHz): δ=151.3 (s, Ar C), 136.4 (s, ArC), 129.0 (s, Pyr C), 126.3 (s, Ar C), 125.8 (s, Ar C), 120.2 (s, Ar C),120.1 (s, Ar C), 108.6 (s, Pyr C), 34.7 (s, C(CH₃)₃), 29.7 (s,C(C—H₃)₃). Anal. Calcd for C₂₄H₂₉NO₂: C, 79.30; H, 8.04; N, 3.85. Found:C, 79.23; H, 7.97; N, 3.76.

Synthesis of [pyr-ONO]W═CH^(t)Bu(O^(t)Bu) (15)

As indicated in FIG. 46, a benzene solution (2 mL) containing 14 (0.087g, 2.38×10⁻⁴ mol, 1 equiv) was added drop-wise to a benzene (1 mL)solution of (^(t)BuO)W≡C^(t)Bu (0.112 g, 2.38×10⁻⁴ mol, 1 equiv). Thereaction mixture was allowed to stir for 0.5 h; during that time, thesolution color turned to deep violet. All volatiles were evaporatedunder vacuum for 1 h. The violet powder was dissolved in pentane andfiltered. The filtrate was collected and concentrated to 1 mL. Coolingthe solution to −35° C. precipitates crystals of 15. A second batch ofcrystals was obtained after further concentrating and once again coolingthe solution to −35° C. (Yield=0.074 g, 45%). ¹H NMR (C₆D₆, 500 MHz):δ=8.27 (d, 2H, Ar—H, ³J=7.57 Hz), 7.77 (s, 2H, Pyr-H), 7.67 (s, 1H,W═CH^(t)Bu), 7.24 (d, 2H, Ar—H, ³J=6.83 Hz), 7.16 (t, 2H, Ar—H, ³J=7.57Hz), 1.79 (s, 9H, W═CHC(CH₃)₃), 1.65 (s, 18H, Ar—C(CH₃)₃), and 0.50 (s,9H, —OC(CH₃)₃) ppm. ¹³C{¹H} NMR (C₆D₆, 126 MHz): δ=268.61 (s, W═CH′Bu),149.6 (s, Ar C), 139.2 (s, Ar C), 138.3 (s, Pyr C), 127.3 (s, Ar C),124.5 (s, Ar C), 122.5 (s, Ar C), 113.5 (s, Pyr C), 80.4 (s, —OC(CH₃)₃),46.0 (s, WCHC(CH₃)₃), 36.0 (s, Ar—C(CH₃)₃), 34.4 (s, —C(CH₃)₃), 33.5 (s,—C(CH₃)₃), and 31.3 (s, Ar—C(CH₃)₃) ppm. Anal. Calcd. for C₃₃H₄₅NO₃W: C,57.65%; H, 6.60%; N, 2.04%. Found; C, 57.54%; H, 6.53%; N, 2.02%.

Synthesis of {MePPh₃} {[pyr-ONO]W≡C^(t)Bu(O^(t)Bu)} (16)

As indicated if FIG. 46, a pentane solution (5 mL) of Ph₃PCH₂ (0.025 g,9.1×10⁻⁵ mol, 1.1 equiv) was added drop-wise to a stirring pentanesolution of 15 (0.056 g, 8.2×10⁻⁵ mol, 1.0 equiv) resulting in theprecipitation of a yellow powder. The mixture was stirred for 4 h andthe solid was separated by filtration, and washed with fresh pentane.The paste-like solid was dried under vacuum for 1 h to afford a finewhite powder (Yield=0.061 g, 79%). ¹H NMR (CDCl₃, 500 MHz): δ=7.70 (t,3H, ³J=7.32 Hz, Ar—H), 7.50-7.53 (m, 6H, Ar—H), 7.43 (d, 2H, ³J=7.57 Hz,Ar—H), 7.24-7.29 (m, 6H, Ar—H), 6.97 (d, 2H, ³J=7.57 Hz, Ar—H), 6.63 (t,2H, ³J=7.57 Hz, Ar—H), 6.57 (s, 2H, Pyr-H), 2.25 (d, 3H, CH₃PPh₃,²J_(HP)=12.69 Hz), 1.65 (s, 9H, W≡CC(CH₃)₃), 1.49 (s, 18H, Ar—C(CH₃)₃),and 0.65 (s, 9H, —OC(CH₃)₃) ppm. ³¹P{¹H} NMR (CDCl₃, 121 MHz): δ=20.9ppm. ¹³C{¹H} NMR (CDCl₃, 126 MHz): δ=301.1 (s, WC^(t)Bu), 159.2 (s, ArC), 137.8 (s, Ar C), 135.7 (s, Pyr C), 135.0 (s, Ar C), 132.8 (d, Ar C,³J_(CP)=10.6 Hz), 130.3 (d, Ar C, ²J_(CP)=13.2 Hz), 126.9 (s, Ar C),122.8 (s, Ar C), 121.2 (s, Ar C), 118.8 (d, J_(CP)=90.0 Hz, Ar C), 117.6(s, Ar C), 106.4 (s, Pyr C), 76.8 (s, OCMe₃), 49.7 (s, W≡CC(CH₃)₃), 35.3(s, Ar—C(CH₃)₃), 33.7 (s, OC(CH₃)₃), 33.3 (s, W≡CC(CH₃)₃), 30.4 (s,Ar—C(CH₃)₃), and 8.1 (d, H₃CPPh₃, ¹J_(PC)=56.9 Hz) ppm. Anal. Calcd. forC₅₂H₆₂NO₃PW: C, 64.80%; H, 6.48%; N, 1.45%. Found; C, 64.73%; H, 6.39%;N, 1.39%. The molecular structure of 16 as a co-crystal with diethylether by x-ray diffraction is shown in FIG. 47.

X-Ray Analysis of 16

X-Ray Intensity data were collected at 100 K on a Bruker DUOdiffractometer using MoKα radiation (λ=0.71073 Å) and an APEXII CCD areadetector. Raw data frames were read by program SAINT and integratedusing 3D profiling algorithms. The resulting data were reduced toproduce hid reflections and their intensities and estimated standarddeviations. The data were corrected for Lorentz and polarization effectsand numerical absorption corrections were applied based on indexed andmeasured faces. The structure was solved and refined in SHELXTL6.1,using full-matrix least-squares refinement. The non-H atoms were refinedwith anisotropic thermal parameters and all of the H atoms werecalculated in idealized positions and refined riding on their parentatoms. The asymmetric unit consists of the W1 complex anion, atriphenylmethylphospate cation and an ether solvent molecule. In thefinal cycle of refinement, 12092 reflections (of which 8643 are observedwith I>2σ(I)) were used to refine 583 parameters and the resulting R₁,wR₂ and S (goodness of fit) were 3.47%, 5.63% and 1.008, respectively.The refinement was carried out by minimizing the wR₂ function using F²rather than F values. R₁ is calculated to provide a reference to theconventional R value but its function is not minimized. SHELXTL6 (2008).Bruker-AXS, Madison, Wis., USA. FIGS. 48-52 gives the pertinent x-raydata for the 16 co-crystal.

It should be understood that the examples and embodiments describedherein are for illustrative purposes only and that various modificationsor changes in light thereof will be suggested to persons skilled in theart and are to be included within the spirit and purview of thisapplication.

We claim:
 1. An ONO trianionic pincer ligand precursor, consisting of atri-protonated ONO trianionic pincer ligand precursor with OH and NHfunctionality, wherein each O⁻ from the OH is separated from the N⁻ fromthe NH by three bridging carbons, wherein the O⁻s and the N⁻ and thebridging carbons are capable of assuming a coplanar substructure:

where X is C, and wherein the tri-protonated ONO trianionic pincerligand precursor with OH and NH functionality has the structure:

wherein R is independently C₂-C₃₀ alkyl, C₂-C₃₀ alkenyl, C₂-C₃₀ alkynyl,C₁-C₃₀ alkoxy, C₂-C₃₀ alkenyloxy, C₂-C₃₀ alkynyloxy, ₂-C₃₀ alkylester,C₃-C₃₀ alkenylester, C₃-C₃₀ alkynylester, or perfluorinated, partiallyfluorinated variations thereof.
 2. The ONO trianionic pincer ligandprecursor of claim 1, consisting of a tri-protonated ONO trianionicpincer ligand precursor with OH and NH functionality, wherein each O⁻from the OH is separated from the N⁻ from the NH by three bridgingcarbons, wherein the O⁻s and the N⁻ and the bridging carbons are capableof assuming a coplanar substructure:

where X is C, and wherein the tri-protonated ONO trianionic pincerligand precursor with OH and NH functionality has the structure:

wherein R is independently C₂-C₃₀ alkyl, C₂-C₃₀ alkenyl, C₂-C₃₀ alkynyl,C₁-C₃₀ alkoxy, C₂-C₃₀ alkenyloxy, C₂-C₃₀ alkynyloxy, ₂-C₃₀ alkylester,C₃-C₃₀ alkenylester, C₃-C₃₀ alkynylester, or perfluorinated, partiallyfluorinated variations thereof.
 3. The ONO trianionic pincer ligandprecursor of claim 1, consisting of a tri-protonated ONO trianionicpincer ligand precursor with OH and NH functionality, wherein each O⁻from the OH is separated from the N⁻ from the NH by three bridgingcarbons, wherein the O⁻s and the N⁻ and the bridging carbons are capableof assuming a coplanar substructure:

where X is C, and wherein the tri-protonated ONO trianionic pincerligand precursor with OH and NH functionality has the structure:

wherein R is independently C₂-C₃₀ alkyl, C₂-C₃₀ alkenyl, C₂-C₃₀ alkynyl,C₁-C₃₀ alkoxy, C₂-C₃₀ alkenyloxy, C₂-C₃₀ alkynyloxy, ₂-C₃₀ alkylester,C₃-C₃₀ alkenylester, C₃-C₃₀ alkynylester, or perfluorinated, partiallyfluorinated variations thereof.
 4. The ONO trianionic pincer ligandprecursor of claim 2, wherein the structure is:


5. The ONO trianionic pincer ligand precursor of claim 3, wherein thestructure is:


6. A trianionic ONO pincer ligand comprising transition metal complexcomprising: at least one ONO trianionic pincer ligand derived from theONO trianionic pincer ligand precursor of claim 1; and a transitionmetal from group III through group X of the periodic table.
 7. Thetrianionic ONO pincer ligand comprising transition metal complex ofclaim 6, wherein the transition metal is an early transition metalcomplex from group III through group VI.
 8. The trianionic ONO pincerligand comprising transition metal complex of claim 6, wherein thestructure is:


9. The trianionic ONO pincer ligand comprising transition metal complexof claim 6, wherein the structure is:


10. The trianionic ONO pincer ligand comprising transition metal complexof claim 6, wherein the structure is:


11. A method of preparing an ONO pincer ligand precursor according toclaim 1, comprising condensing a nucleophilic oxygen or nucleophilicnitrogen comprising compound with an electrophilic carbon comprisingcompound further comprising the bridge structure of the resulting ONOpincer ligand.
 12. A method of preparing an ONO pincer ligand comprisingtransition metal complex of claim 6, comprising combining a precursormetal compound comprising a metal alkoxide or metal amide with an ONOpincer ligand precursor of the structure:

wherein R is independently C₁-C₃₀ alkyl, C₂-C₃₀ alkenyl, C₂-C₃₀ alkynyl,C₆-C₂-C₃₀ alkenyloxy, C₂-C₃₀ alkynyloxy, C₂-C₃₀ alkylester, C₃-C₃₀alkenylester, C₃-C₃₀ alkynylester, or perfluorinated, partiallyfluorinated, and/or otherwise substituted variations thereof; whereinproton and ligand exchange between the anionic ONO pincer ligandprecursor and the metal alkoxide or metal amide.
 13. The method ofpreparing an ONO pincer ligand comprising transition metal complex ofclaim 12, wherein the precursor metal compound further comprises a metalalkylidyne, further comprising adding the OH or NH of the ONO pincerligand precursor across the metal alkylidyne to form the anionic ONOpincer ligand comprising metal complex.